"Most of the politicians I know understand that and I think that, dare I say, the responsibility of power is probably quite a sobering thing and you come to a realisation, 'I understand how this thing works'."
I agree that this is an implication. But it implies that Corbyn and his ilk don't understand the responsibility of power and don't understand the principle of deterrence. (They may not, but pointing it out influences votes.)
I heard him say that and I took it the other way - he was implying that if Corbyn came to power, the responsibility of his position & the logic behind the deterrent may be better explained and he may come to change his mind/view on his position (hard as that is to believe). Seems a very uphill battle but I think that is what CDS was hinting at - he was actually giving Corbyn the benefit of the doubt on the strength of his position and giving him leeway to modify/adapt his position.